The present disclosure relates generally to apparatuses, devices, and associated equipment used to produce supercritical steam. The supercritical steam may be used with advanced methods of enhancing oil recovery, among other processes.
Nearly two-thirds of the world's energy demand is satisfied by oil and natural gas, including the vast majority of transportation fuel in developed countries. However, the demand for energy continues to increase. Concurrently, hydrocarbon (i.e., oil and gas) reservoirs located within the Earth's strata differ in the ease with which their hydrocarbons can be extracted. The reservoirs that are easiest to produce from are more quickly exhausted.
Extraction of hydrocarbons (i.e., oil and gas) occurs in multiple stages. During the primary recovery stage, the natural underground pressure of the hydrocarbon-containing reservoir/formation and/or conventional pumping systems are used to extract low viscosity (i.e., pumpable) hydrocarbons.
Over the lifetime of a given well, the natural pressure of the hydrocarbon-containing reservoir will eventually fall, and the remaining hydrocarbons will be of high enough viscosity that conventional pumping systems will be unable to extract the hydrocarbons. Enhanced oil recovery methods aim to recover the remaining oil and gas from such reservoirs. Enhanced oil recovery refers to hydrocarbon production techniques in which the physical properties of the oil within the reservoir are altered to allow additional oil to be recovered from the underground rock formation.
Steamflooding is one example of an enhanced oil recovery technique. In steamflooding, steam is injected into a hydrocarbon-containing reservoir in order to improve oil displacement and/or fluid flow. The heat energy in the steam is transferred to the reservoir/formation. Heated hydrocarbons in the reservoir become less viscous and also swell/expand. This aids in releasing the hydrocarbons from the reservoir and also eases movement through the formation to the production wells where the hydrocarbons are extracted using conventional pumping technology. The steam may condense as it moves through the reservoir, resulting in waterflooding which also drives hydrocarbons out to the production wells. Light fractions of crude oil may be vaporized and thus provide an additional driving force to aid the flow of oil.
Existing infrastructure (e.g., production wells) can be used or modified for use in steamflooding applications. Use of enhanced oil recovery techniques can prolong the life of an oil field considerably (e.g., from 25 to 30 years), reduce oil exploration costs, and alleviate/lessen political problems and/or environmental concerns.
Current subcritical steamflood boilers typically provide 70 to 80 percent quality steam (i.e., a “wet” two phase steam/liquid water mixture containing 70-80% steam and 30-20% water) at pressures of approximately 2400 psi or less. Typically, a single boiler provides the wet steam to a large piping distribution network that supplies steam to a plurality of steam injectors. The steam injectors may be located a significant distance from the boiler. It can be difficult to split the steam/water mixture from current subcritical steamflood boilers evenly among the various injector wells and nozzles. When there is a flow split in the piping system, it is very difficult to get an even mixture of steam/water in each of the downstream legs to the steam injectors. In a worst case scenario, for example, one downstream leg could receive all vapor (i.e., steam) while a different leg could receive all condensate (i.e., water). This outcome is undesirable because it is important that each steam injection well receives a minimum “latent heat” for maximum recovery efficiency.
Steam separators may be utilized with subcritical steamflood boilers to provide a higher quality of steam to a reservoir. However, this increases equipment costs and leads to the liquid water portion of the steam/water mixture not being delivered, which significantly reduces overall system efficiency.
It is therefore desirable to develop new, efficient, and economical apparatuses, systems, and methods that can be used in enhanced oil recovery or to generate dry supercritical steam for various applications.